We are receiving a lot of questions about relevant analyses in the Analyse-it Method Validation edition to help in evaluating new diagnostic tests in the fight against COVID-19. Below are some quick links that will help, but contact us if you have questions - we are working as normal.
Also see our latest blog post: Sensitivity/Specificity and The Importance of Predictive Values for a COVID-19 test
A correlation coefficient measures the association between two methods.
The correlation coefficient is sometimes re-purposed as an adequate range test (CLSI, 2002) on the basis that the ratio of variation between subjects, relative to measurement variation, is an indicator of the quality of the data (Stöckl & Thienpont, 1998). When the correlation coefficient is greater than 0.975 the parameters of an ordinary linear regression are not significantly biased by the error in the X variable, and so linear regression is sometimes recommended.
However, with the wide range of proper regression procedures available for analyzing method comparison studies, there is little need to use inappropriate models.